Chemical probing of HER2-amplified cancer cells identifies TORC2 as a particularly effective secondary target for combination with lapatinib

The clinical impact of HER2 inhibitors in the treatment of HER2-amplified breast cancers has been largely confined to chemotherapy combination regimens, since HER2 inhibitors appear to have very modest efficacies by themselves. This is due to the resilient nature of the functionally relevant HER2-HER3 tumor driver, bidirectionally linked with downstream PI3K/Akt pathway signaling, which can break through the inhibitory effects of most current HER2 or HER3 targeting therapies. A vertical combination approach targeting HER2 and a downstream pathway is a highly rational strategy for much more effective targeted therapy of this disease. However the importance of these downstream pathways in many human tissues and cells significant limits their usefulness as secondary targets by narrowing the therapeutic index of such combination therapies. The secondary target that can afford the highest potential for clinical translation is the one with the highest synergy against tumor cells in combination with HER2-inhibition, allowing the widest therapeutic index for clinical translation. We conducted a comparative analysis of such secondary targets in combination with the HER2 inhibitor lapatinib and find that the inhibition of mTor affords the highest degree of synergy. In further dissecting the individual roles of TORC1 and TORC2 complexes using pharmacologic and genetic tools, we find that it is specifically the inactivation of TORC2 that most synergistically enhances the efficacy of lapatinib. Although inhibitors that selectively target TORC2 are not currently available, these data make a compelling case for their development.     

Molecular effects of Lapatinib in the treatment of HER2 overexpressing oesophago-gastric adenocarcinoma

Background:

Lapatinib, a dual EGFR and HER2 inhibitor has shown disappointing results in clinical trials of metastatic oesophago-gastric adenocarcinomas (OGAs), and in vitro studies suggest that MET, IGFR, and HER3 confer resistance. This trial applied Lapatinib in the curative neoadjuvant setting and investigated the feasibility and utility of additional endoscopy and biopsy for assessment of resistance mechanisms ex vivo and in vivo.

Methods:

Patients with HER2 overexpressing OGA were treated for 10 days with Lapatinib monotherapy, and then in combination with three cycles of Oxaliplatin and Capecitabine before surgery. Endoscopic samples were taken for molecular analysis at: baseline including for ex vivo culture +/− Lapatinib to predict in vivo response, post-Lapatinib monotherapy and at surgery. Immunohistochemistry (IHC) and proteomic analysis was performed to assess cell kinetics and signalling activity.

Results:

The trial closed early (n=10) due to an anastomotic leak in two patients for which a causative effect of Lapatinib could not be excluded. The reduction in Phosphorylated-HER2 (P-HER2) and P-EGFR in the ex vivo-treated biopsy demonstrated good correlation with the in vivo response at day 10. Proteomic analysis pre and post-Lapatinib demonstrated target inhibition (P-ERBB2, P-EGFR, P-PI3K, P-AKT, and P-ERK) that persisted until surgery. There was also significant correlation between the activation of MET with the level of P-Erk (P=0.0005) and P-PI3K : T-PI3K (total PI3K) ratio (P=0.0037). There was no significant correlation between the activation status of IGFR and HER3 with downstream signalling molecules.

Conclusions:

Additional endoscopy and biopsy sampling for multiple biomarker endpoints was feasible and confirmed in vitro data that MET is likely to be a significant mechanism of Lapatinib resistance in vivo.     

Quercetin‐3‐methyl ether inhibits lapatinib‐sensitive and ‐resistant breast cancer cell growth by inducing G2/M arrest and apoptosis

Lapatinib, an oral, small‐molecule, reversible inhibitor of both EGFR and HER2, is highly active in HER2 positive breast cancer as a single agent and in combination with other therapeutics. However, resistance against lapatinib is an unresolved problem in clinical oncology. Recently, interest in the use of natural compounds to prevent or treat cancers has gained increasing interest because of presumed low toxicity. Quercetin‐3‐methyl ether, a naturally occurring compound present in various plants, has potent anticancer activity. Here, we found that quercetin‐3‐methyl ether caused a significant growth inhibition of lapatinib‐sensitive and ‐resistant breast cancer cells. Western blot data showed that quercetin‐3‐methyl ether had no effect on Akt or ERKs signaling in resistant cells. However, quercetin‐3‐methyl ether caused a pronounced G₂/M block mainly through the Chk1‐Cdc25c‐cyclin B1/Cdk1 pathway in lapatinib‐sensitive and ‐resistant cells. In contrast, lapatinib produced an accumulation of cells in the G₁ phase mediated through cyclin D1, but only in lapatinib‐sensitive cells. Moreover, quercetin‐3‐methyl ether induced significant apoptosis, accompanied with increased levels of cleaved caspase 3, caspase 7, and poly(ADP‐ribose) polymerase (PARP) in both cell lines. Overall, these results suggested that quercetin‐3‐methyl ether might be a novel and promising therapeutic agent in lapatinib‐sensitive or ‐resistant breast cancer patients. © 2011 Wiley Periodicals, Inc.     

Fosaprepitant for the prevention of chemotherapy-induced nausea and vomiting

For patients receiving cancer chemotherapy, the ongoing development of antiemetic treatment is of significant importance. Patients consider nausea and vomiting among the most distressing symptoms of chemotherapy, and as new antiemetics have been very successful in prevention of vomiting, agents effective against nausea have become one of the major unmet needs. The neurokinin (NK)₁ receptor antagonist aprepitant potentiates the antiemetic efficacy of the combination of a serotonin receptor antagonist and a corticosteroid. Fosaprepitant (intravenous prodrug of aprepitant) given as a single intravenous dose of 150 mg can replace the aprepitant 3-day oral regimen. This article focuses on the development and clinical application of fosaprepitant.     

Neratinib for the treatment of breast cancer

Introduction: Neratinib is an orally available, pan-HER inhibitor with clinical activity in patients with HER2-amplified and HER2-mutated breast cancer.

Areas covered: A summary of publically available and relevant clinical data on neratinib.

Expert opinion: Neratinib (N) is clearly distinct from lapatinib (L), a difference based on its broad anti-HER effect, its covalent target binding and its toxicity profile. The main toxicity of neratinib is gastro-intestinal and is essentially limited to diarrhea. Although not directly compared with single agent lapatinib, skin toxicity is much less pronounced with N. The direct clinical comparison of N-capecitabine versus L-capecitabine is the subject of the ongoing NALA-trial. In patients with advanced disease, neratinib has clinically relevant activity in patients with trastuzumab(T)-pretreated and unpretreated disease. In patients having completed one year of adjuvant trastuzumab, an additional year of neratinib further reduces the risk of recurrence of invasive disease. The activity of neratinib in HER2-mutated advanced disease is subject of ongoing clinical trials but preclinical and early clinical results are promising. Neratinib is a usefull drug and a valuable addition to the different anti-HER2-drugs avalaible for patients with HER2-overexpressing and HER2-mutated breast cancer.     

Her2 positive breast cancer: practices

The molecular classification of Perou and Sørlie breast tumors has to streamline, systematize and make effective use of targeted therapies against specific molecular subtypes, including breast HER2 positive. Trastuzumab and lapatinib are currently the two therapies targeting HER2, which have demonstrated their effectiveness in clinical practice. This literature review aims to make the data points on pertinent and useful data for physicians in daily     

A Validated RP-HPLC Method for the Estimation of Lapatinib in Tablet Dosage form using Gemcitabine Hydrochloride as an Internal Standard

A simple, selective, rapid, precise and economical reverse-phase high-performance liquid chromatography method has been developed for the determination of lapatinib in tablet using gemcitabine hydrochloride as an internal standard. Chromatography was carried out on an ODS C-18 RP column (4.6 mm i.d. ×250 mm) using a mixture of acetonitrile and water (50:50 v/v) as the mobile phase at a flow rate of 1.0 ml/min. The drug was monitored at 232 nm. The retention times for lapatinib and gemcitabine hydrochloride were found to be 4.25±0.05 and 6.10±0.05 min, respectively. The method produced linear responses in the concentration range of 2-60 μg/ml of lapatinib. The limit of detection and limit of quantitation were 0.265 and 0.884 μg/ml, respectively.